Fluid pressure servomotor of the follow-up type



11, 1948. w EATON 2,441,263

FLUID PRESSURE SERVO-MOTOR OF THE FOLLOWUP TYPE Filed April 27, 1945RUDD ER Patented May H, 1948 FLUID PRESSURE SERVOMOTOR OF THE FOLLOW-UPTYPE Wilfred A. Eaton, Elyria, Ohio, assignor to Bendix-WestinghouseAutomotive Air Brake Company, Elyria, Ohio, a corporation of DelawareApplication April 27, 1945, Serial No. 590,672

1 17 Claims.

This invention relates in general to power means for controlling theoperation of a remotely positioned device, and more particularly tofluid pressure control mechanism for controlling the operation of aremotely positioned. rudder or other device on a vehicle such as a boator airplane.

One of the objects of the present invention is to provide power operatedmeans for efiecting a graduated control of the movement of a remotelypositioned rudder or other device.

Another object of the invention is to provide fluid pressure operatedcontrol means for such a device so constituted as to eliminate thenecessity for mechanical connections between the device and theoperator's control element.

Yet another object of the invention is to provide, in a mechanism of theabove type, control means for the power actuator or actuators soconstituted as to render the degree of power supplied to the actuatordependent solely on the de-- gree of control exercised by the operator.

A still further object of the invention is to provide control mechanismof the type referred to in the preceding paragraph, so constituted as torender the degree of power supplied to the actuator or actuatorsindependent of any outside force exerted on the device.

These and other desirable objects and features 'of the invention will bereadily apparent to those skilled in the art when considered in thelight of the following description, but it is to be expressly understoodthat the description is not to be taken as limiting the invention,reference being hadv for this purpose to the appended claims.

In the drawing, the single figure illustrates diagrammatically, andpartially in section, a fluid pressure control mechanism constructed inaccordance with the principles of the present invention.

Referring to the drawing, the mechanism includes generally a fluidpressure reservoir 4, an operators control valve 5, actuators orcylinders 6 and F, control valve mechanism 8, a remotely positionedrudder or device to be actuated 9, and a mechanism 9a adapted tonormally maintain the device or rudder in neutral position.

The reservoir 4 is adapted to receive fluid pressure from acompressor,-not shown, through conduit l0, and is adapted to supplyfluid pressure to an inlet chamber H in the valve mechanism 5 through aconduit l2, and to supplyfiuid pressure to an inlet chamber l3 in thevalve mechanism 8 through conduit H, a conduit M and a flexible hose l5.The valve mechanism 5, to be described hereinafter in more detail, isprovided with valve operating plungers I6 and i1 and outlet conduits l8and I9 connected respectively to the right and left ends of a cylinder20 forming part of actuator 6. A rudder bar M is pivotally mounted onthe structure of the airplane by means of a pin 22, serving on rotationof the bar to depress one or the other of the plungers [6 or H. Thevalve mechanism 5 is of the duplex type having a pair of self-lappingvalves operated respectively by the plungers I 6 and I1, and it will beunderstood that on operation of the rudder bar to depress the plungerl6,

the valve mechanism will be operated to supply fluid pressure to theright end of the cylinder at a pressure substantially proportional tothe degree of movement of the rudder bar from the position shown, whileon movement of the rudder bar in the opposite direction, a graduated andcontrolled pressure will similarly be supplied to the left end of thecylinder.

. With regard to the construction of the valve mechanism 5, it will benoted that the mechanism operated by the plungers l6 and I1 is identicalon both sides of the valve and the right hand portion of the valve willtherefore be described.

' In addition to the inlet chamber l I, the right hand portion isprovided with an outlet chamber 23 connected with the outlet conduit l8,and separated from the inlet chamber by means of, a ported partition 24.An inlet and exhaust valve assembly comprising an inlet valve 25, a stem26, and an exhaust valve 21 on the upper end of the stem, is normallymaintained in the position shown to prevent communication between theinlet and outlet chambers through the ported partition by means of aninlet valve spring 28 interposed between the exhaust valve and the uppersurface of the partition. Operation of the valve assembly isaccomplished by means of a valve operating element 29 provided with abore 30 open at its lower end and adapted on downward movement to engagethe upper surface of the exhaust valve in order to close the lower endof the bore. The element 29 is slidably mounted in a bore 3!, and issuitably conneotedwith a pressure responsive diaphragm 32 clamped in thecasing of the valve mechanism in such a manner as to define a controlchamber 33 having an exhaust chamber 34. The control chamber isconnected with the outlet chamber 23 by means of a restricted passage 35in such a manner that the lower surface of the diaphragm is subjected atall times to the pressure in the outlet chamber, and the exhaust chamberis connected to atmosphere through an exhaust port 36; In order that thevalve operating element may be actuated by means of the plunger l6, agraduating spring 31 is interposed between the upper surface of thediaphragm and the lower surface of a washer 33 slidably. mounted on theelement 29 and in engagement with a shoulder 39 formed on the plunger,the result being that on downward movement of the plunger the graduatingspring is compressed in such a manner as to exert a downward force onthe diaphragm which tends to correspondingly move the element 29downward into engagement with the exhaust valve 21. Upward movement ofthe washer 38 on the element 29 is restricted by means of a flangedportion III formed on the element, and it will be understood that withthis construction, the graduating spring 31 can be initially installedin such a manner as to be slightly compressed between the upper surfaceof the diaphragm and the lower surface of the washer 38 in such a mannerthat initial operation of the plunger I6 will cause the valve mechanismto immediately deliver a pressure corresponding to the degree ofpreloading of the graduating spring.

It will be understood from the foregoing that the operation of theself-lapping valve mechanism just described with the preloadedgraduating spring is substantially identical with that disclosed in thepatent to William J. Andres and Roy S. Sanford, No. 2,133,275, datedOctober 18, 1938, but it is also pointed out that if desired, thegraduating spring may be so dimensioned with respect to the position ofthe diaphragm and the washer 38 as to avoid any preloading or initialpro-compressing of the graduating spring during installation. The lowerportion of the plunger is provided with a skirt 4| which serves to guidethe movement of the valve in a, bore 42 formed in the valve mechanism,and communication between the exhaust port 36 and the exhaust chamber 34is eifected by means of a port 43 formed in the wall of the plungerskirt, the exhaust chamber in turn being adapted for connection with theoutlet chamber 23 through ports 44 formed in the wall of the bore 30.Thus the operation of this valve is substantially identical with thatdescribed and disclosed in Fig. 1 of the above re-. ferred to patent,and it will be apparent that with the plunger IS in the position shown,communication between the inlet chamber i l and the outlet chamber 23will be prevented, while communication will be permitted between theoutlet chamber and atmosphere through the bore 30, ports 44, exhaustchamber 34, port 43 and exhaust port 36. On downward movement of theplunger, the valve operating element will be moved downward to firstclose the exhaust valve and subsequently open the inlet valve in orderto admit fluid pressure from the inlet chamber to the outlet chambet,and due to the fact that the outlet chamber is connected with thecontrol chamber 33 through the restricted passage 35,-the pressuresupplied to the outlet chamber and control chamber will exert suflicientforce on the diaphragm to overcome the force exerted by the graduatingspring,

whereupon the element will be moved upward sufficiently to permitclosing of the inlet valve in order to maintain a pressure in the outletchamber substantially proportional to the degree of movement of theplunger i8 from the position shown. In like manner, the left handportion of the valve is provided with an outlet chamber 43, inlet andexhaust valves 46 and 41. a valve operating element 48, a pressureresponsive diaphragm 48, and a graduating spring 50 interposed betweenthe plunger I1 and the diaphragm, and since the plunger and valveoperating element are constructed in the same manner as those shown inthe right hand portion of the valve, it will be understood that with theplunger il in the position shown, the outlet chamber will be incommunication with the atmosphere through the bore formed on the valveoperating element, the ports 44, the port 43 in the skirt of the plungerand an exhaust port 5| formed in the upper portion of the valve. Sincethe outlet chambers 23 and 45 are connected with the right and left endsof the cylinder 20 through conduits l8 and I3 respectively, it will beclear that the valve mechanism may be operated by the rudder bar 2! tosupply any desired pressure to either end of the cylinder, this pressurebeing substantially proportional to the degree of movement of the rudderbar from the position shown in either direction depending on which endof the cylinder is to be energized by the operator.

The valve mechanism 8 is similar to the valve mechanism 5 except for theomission of the graduating springs and is likewise of the duplex type.The upper half of the mechanism will be described in detail since it isidentical with the lower portion. As shown in the drawing, thevalvemechanism includes a casing 52 provided with an outlet chamber 53,a diaphragm chamber 54, and an exhaust chamber 55, the latter beingprovided with an atmospheric port 36. A ported partition 51 separatesthe inlet chamber i3 from the outlet chamber, communication betweenthese chambers through the partition being normally prevented by meansof an inlet valve 58 having a stem 58, which is normally maintained inthe position shown by means of an inlet valve spring 60 interposedbetween the left surface of the partition and the right surface of anexhaust valve 6! mounted on the left end of the stem. The left end oftheoutlet chamber 33 is defined by means of a partition 62, and theoutlet chamber communicates with the diaphragm chamber througharestricted passage 83 in the partition. A valve operating element 64 isslidably mounted in the partition and is provided with a central bore65. the right end oi! which is adapted on movement of the element to theright to contact the exhaust valve it in order to prevent communicationbetween the outlet chamber and the bore, the bore communicating withatmosphere through ports 66 formed in the wall thereof, exhaust chamber55 and exhaust port 56. A flexible diaphragm 61 serves to separate thediaphragm and exhaust chambers, the diaphragm being suitably clamped atthe outer periphery to the casing, and adjacent its center to the valveoperating element. A valve operating plunger 68 is slidably mounted inthe casing. and a shoulder 63 formed thereon serves to operate the valveoperating element through engagement with a flange 10 formed on the leftend thereof. Thus with the valves in the position shown, communicationis prevented between the inlet and outlet chambers and is permittedbetween the outlet chamber and atmosphere through the channels alreadydescribed, while on movement of the valve operating element to theright, the right end 01' the bore is closed by the exhaust valve toprevent communication between the outlet chamber and atmosphere, furthermovement of the element in this direction serving to open the inletvalve in order to permit communication to be established between theinlet and outlet chambers. Since the diaphragm is subjected at all timesto the pressure in the outlet chamber through the re-. stricted passage93, it is apparent that this pressure will act on the diaphragm to movethe valve operating element to exhaust position as soon as the forcetending to move the element to the right is relieved. The upper end ofthe plunger 99 is provided with an extension II which serves to operatethe plunger and it will be understood that a similar plunger in thelower half of the valve mechanism is provided with an extension I2 whichserves to operate that portion of the valve mechanism.

The valve mechanism 8 is arranged to control the supply of fluidpressure to the fluid motor I, the latter motor including a casing 13having a piston It slidably mounted therein. The casing is pivotallymounted on the structure of the airplane, not shown, by means of abracket IS. The left end of the cylinder is connected with the outletchamber 53 of the valve mechanism 9 through a conduit 16 and a flexiblehose 11, the right end'of the cylinder being connected with the outletchamber of the lower portion of the valve mechanism through a conduit I9and a flexible hose i9, and it will be understood that on movement ofthe plunger II to the right, fluid pressure will be supplied tothe leftend of the motor 8 from the reservoir 9 through conduit i9, conduit i9,flexible hose I5, inlet chamber it, ported partition 51, outlet chamber53, hose ill and conduit I9, while with the plunger in the positionshown, the left end of the cylinder will be connected to atmospherethrough conduit I9, flexible hose ll, outlet chamber 59, bore 65, port99, exhaust chamber 55 and exhaust port 56. In like manner, the lowerportion of the valve mechanism with the plunger 12 in the position shownwill serve to connect the right end of the cylinder with atmospherethrough the conduit I8, the flexible hose I9, the valve mechanism and anexhaust port 89 provided in the casing thereof. The left end of thecasing of the valve mechanism '9 is provided with a boss 8i on which avalve operating lever 82 is pivotally mounted by means of a suitable pin89, the construction being such that on movement of the lever in aclockwise direction relative to the valve casing, the plunger ii will bemoved to the right to supply fluid pressure to the left end of the motoras above described, while on movement. of the lever in the reversedirection, the plunger i2 will be similarly operated to supply fluidpressure to the right end of the cylinder. The piston of the cylinder I3is provided with a piston rod 89 pivotally connected at its right end tothe lower end of the lever 92 by means of a, suitable pivot pin 95, thepiston rod being slidably mounted in a bore 96 formed in the right endof the cylinder and provided with a seal 8? for the purpose ofpreventing leakage of fluid pressure .from the cylinder at this point.In like manner, the upper end of the lever is connected by means of apivot pin 88 with a piston rod 99 connected at its left end to a piston99 slidably mounted in the casing 29 of the motor 9, and the respectiveareas of the pistons I4 and 99 are so chosen as to be inverselyproportional to the lever arms oi the lever 92 formed between the pivotpin 93 and the pivot pins 95 and 98, the result being that when equalpressures are supplied to the right and left ends' of the fluid motors 9and I, the moments exerted on the lever arm about the pivot pin 93 arebalanced and there is no tendency for rotation of the lever arm aboutthis pivot. In order that the power delivered by the fluid motors 9 andI may be applied to move the rudder 9, a connecting rod 9i is rigidlyattached to the right end of the casing of the valve mechanism 9 and isguided for longitudinal movement by bores .92 and 93 formed in a casing94 mounted on the structure of the airplane by means of a suitablebracket 95 and forming part of the mechanism 9a. The right end of theconnecting rod is pivotally connected by a pivot pin 91 to an arm 99rigidly attached to the rudder, the pivot pin engaging a slot 99 formedon the upper end of the lever. In

order that the rudder may be normally maintained in neutral position,the rod 9| is provided with a suitable collar 99 mounted for movementtherewith, and neutralizing springs I99 and IM are interposed betweenthe left and right ends of the casing and flanges I92 and I93 of springcages 594 and I slidably mounted in the casing. The cage I94 is providedwith a flange I99 adapted to engage a shoulder I91 formed on the casingin order to prevent further movement of the spring cage to the rightwhile movement of the spring cage I95 to the left beyond the positionshown is prevented by a flanged portion I98 adapted to engage a shoulderI 99 formed on the casing. The springs I99 and IN may be installed in aprecompressed or preloaded condition in order that a predetermined forcemay be required to move the rod 9I and the rudder 9 from neutralposition.

In the event the operator is 'desirous of turning the rudder 9 in aclockwise direction, for example, the rudder bar 2| may be rotated in acounterclockwise direction to depress the plunger II of the valvemechanism 5, and it will be understood from the foregoing descriptionthat on initial movement of the rudder bar to effect closing of theexhaust valve 41 and opening of the inlet valve 46, the preloading ofthe graduating spring 59 will cause a pressure to be built up in theoutlet chamber 95 which corresponds to the preloading of the graduatingspring, so that fluid pressure will be initially supplied to the leftend of the fluid motor 9. On further movement of the rudder bar in thesame direction, the pressure supplied to the fluid motor Ii will besubstantially proportional to the degree of movement of the rudder bar,with the result that over most of the range of movement of the rudderbar, the pressure supplied to the motor will be substantiallyproportional to the degree of movement of the rudder bar from neutralposition. When fluid pressure is thus supplied to the left end of thefluid motor 6, the'piston 99 and the piston rod 89 will be moved to theright, and this motion will tend to rotate the valve operating lever 82clockwise about the pivot pin 93 in order to depress the valve operatingplunger II of the valve mechanism 8. During this action, the parts 94and It may be moved a slight distance to the left in the event thatmotor I is not charged with pressure. Such movement of the parts 84 andIt will be slight, however, in view of the slight clearances in thevalve mechanism including elehaustvalve 62 will closed and the inletvalve 58 will be opened to permit the flow of fluid pressure from theinlet chamber ii to the outlet chamber 58 and thence to the left end ofthe fluid motor I through the flexiblehose TI and the conduit I6,whereupon the piston 18 and the piston rod will be moved to the right inorder to rotate the valve operating lever 82 in the opposite directionabout the pivot pin 88. In case the motor I is charged with pressureprior to clockwise movement of the lever 82, the lever will pivot aboutits lower end 88 and move the valve assembly 8 to the right and effectoperation of the plunger ll. As heretofore explained, the areas of thepistons 88 and II are inversely proportional to the lengths .of thelever arms to which their respective piston rods are connected, andconsequently the moments on the lever about the pivot pin 83 .due to theaction of the two fluid motors will be equal and opposite and there willbe no tendency to rotate the lever when these pressures are equal. Withthe upper portion of the valve mechanism operated to supply fluidpressure to the left end of the motor I as above described, it

mechanism 8 will continue to supply fluid pressure to the left end ofthe fluid motor I, in order to move the piston l4 and the rod 84' to theright until such time as this action has moved the lower end of thelever 82 to the right-suiflciently to cause the lever 82 to again assumethe position shown in the drawing with relation to the casing of 'thevalve mechanism 8. When this occurs, the pressure acting on thediaphragm 81 of the valve mechanism will cause the plunger H to followthe movement of the lever to the left and the inlet and exhaust valve 58and 82 will both be maintained in closed position in a mannenwell knownto those skilled in the art. Due to the travel required to open andclose the exhaust valve, it is apparent that when this lapping actionoccurs, the lever 82 will not return fully to the position shown in-thedrawing, but will be returned from that position just sufllciently tomaintain the exhaust and inlet valve in closed or lapped position. Whilethe follow-up action thus obtained which serves to control the degreeofpower supplied to the fluid motor I is characteristic of many previousmechanisms, it is particularly pointed out that most of these mechanismsare so constructed that the application of an outside force to thedevice to be actuated is such as the rudder 8, operates the valvemechanisms to energize the power actuator in such a manner as toopposethe action of this force. In many cases this action is quite desirable,but in the present instance, the mechanism has been so constituted as torender the control valve mechanisms for the, fluid motors substantiallyindependent of the action of any outside force exerted on the devicebeing actuated. Due to the relationshipof the piston. areas and therelationship of the lever arms, the pressures-in the two fluidmotorswillbesubs'tantially the same when the valves of the valve mechanism 8are in lapped position, and assuming that'powervhas been supplied to themotors to rotate the rudder in a clockwise direction; as heretoforedescribed, it

' will be apparent that the application of an outself-lapping valvemechanisms of this particularside force to the rudder to rotate it inthe reverse direction will move the rod 9| and the casing of' the valvemechanism 8 to the left, and thatthe pivot pin 83 will impart thismotion to the lever 82, and will tend also to move the latter bodily tothe left, but in view of the fact that the moments about the pivot pin83 are such as to prevent rotation of the lever about this pin, it isclear that the movement of the lever to the left due to the applicationof the outside force will in no way change the relationship of the partsin the valve mechanism 8 which serves to control the degree ofenergization of the fluid motor I. While it might appear thatcompression of the fluid in the left ends of the cylinders-28 and 13might tend to upset this relationship,'it=;is pointed out that hereagain the compression in both cylinders will be the same in the eventsuch compression occurs, and it is also pointed out that the structureof the valve mechanisms 5 and 8 are such that any increase in pressurein the left end of the cylinder 28, for example, will be immediatelytransmitted to .the diaphragm 48 through the conduit IS, the outletchamber 45. and the restricted passage 35, and that the resulting forceacting on the diaphragm will move the latter and the attached valveoperating element upward sufflciently to permit the fluid beingcompressed to be exhausted to atmosphere through the exhaust valve ofthe valve .mecha-- nism, this being a well-known characteristic of type.In like manner, compression of fluid in the left end of the motor I willbe immediately transmitted to the-diaphragm 61 in the upper portion ofthe valve mechanism 8, through conduit 18, flexible hose TI, outletchamber 58 and restricted passage 63 and the resulting force acting onthe diaphragm will tend to move the diaphragm and valve operatingelement 65 to the left in order to permit a slight exhaust of pressurethrough the exhaust valve, this motion of the valve operating elementlikewise being transmitted to the lever 82 through the valve operatingplunger H. A very delicate balance of forces is thus maintained, and theoperating parts of the valve mechanism 8 operated at all times toautomati cally maintain substantially equal pressures in the left endsof the fluid motors 8 and l. Operation of the rudder bar 2| in theopposite direc-' tion will serve to correspondingly energize or supplyfluid pressure to the right'e'nds of these fluid motors, and it willbe'understood'that the mode of operation is identical with that abovedescribed except that forces imparted to the rudder rotate it in acounterclockwise direction. In the event of failure of =the conduitsleading from the control valve 8 to the fluid motor I, it iscontemplated that the fluid motor 8 may still be operative to effectlimited operation of the rudder 8 and tothis end stops H8 and ill areformed on the body of the valve mechanism 8 in order to limit rotationof the lever 82 about the pivot pin 83 in either direction. Ihe'stopsare so proportioned as to permit operation of the lever to move theinlet valves of the valve mech anisms 8 .to fully open position, and it-will be readily seen that lnthe event of failure of the conduits l6 and18, or in the event of failure of or the other of the stops iscontacted, whereupon I the valve mechanism will be moved by the actionof the fluid motor in one direction orth'e other:

-of the piston areas.

While the mechanism shown in the drawing has been described inconsiderable detail, it will be understood that numerous changes may bemade in the construction without departing inner, preloaded graduatingsprings have been indicated in the valve mechanism in order to insureenergization of the motor during initial movement of the rudder bar fromneutral position sumcient to substantially overcome the preloading 01the springs Wii and ibl which serve to normally maintain the rudder e inneutral position. The construction is such that these springs need notbe preloaded, however, and it is contemplated in some installations thatit may be desirable to so install these springs as to eliminate thepreloading or precompression entirely. While the fluid motors b and lhave been illus-' trated. and described as having pistons of unequalareas, it is also contemplated that these may be constructed to haveequal areas or that they may be so constructed that the area of thepiston in the fluid motor l is less than that of the piston in the fluidmotor 6, in which case the pivot pin 83 is so positioned on the lever 82as to insure that the lengths of the lever arms are inverselyproportionalto the areas of the pistons in order to insure that themoments tending to rotate the lever about the pivot pin will be equaland opposite when the pressures supplied to the two fluid motors are thesame.

It is further pointed out that while the preferred form of the inventionhas been illustrated as having fluid motors provided with pressureresponsive members having areas inversely proportional to the lengths ofthe lever arms of the lever 82 with which they are connected in order toinsure substantially equal pressures in the two motors when the controlvalve mechanism 8 is lapped, lapping oi the valve mechanism t iseffected when the moments on the lever arms of the lever 82 on oppositesides of the pivot pin 83 are equal and opposite, and it will be readilyunderstood by those skilled in the art that the pistons to and it may beconnected to lever arms of equal length, for example, in which caseequalization of the moments about the pin 83 and lapping of the valvemechanism a will be effected when the pressure in motor 6 reaches avalue greater than that in motor l, this value being determined in thisparticular case by the ratio In like manner, pressure responsive membersof equal area may be connected with lever arms of equal or unequallength without in any way departing from the spirit of. the invention.

le the invention has been illustrated and described herein withconsiderable particularity, it is to be expressly understood that thesame is not limited to the forms shown but may receive a variety oimechanical expressions, as will readily appear to those skilled in theart. Reference will, therefore, be had to the appended claims for adefinition of the limits of the invention.

at is claimed is:

1. Power-operated means for controlling the actuation of a deviceincluding a pair of power actuators each having a power-operated movtheactuators. a second power control means for the otherof said actuators,and means for conmeeting said members and device and for operating saidsecond power control means to supply power to the other of saidactuators and to ad- Just the degree of power supplied thereto to avalue substantially equal tothe degree of power supplied to said oneactuator including. movable means ior connecting said power operatedmovable members, means tor connecting said device with said movablemeans, and. an operative connection between said movable means and saidsecond power control means for operating the latter in accordance withrelative movement of said movable means and connecting means.

2. Power-operated means for controlling the actuation of a deviceincluding a pair of power actuators each havinga power-operated movablemember, power control means for one of the actuators, and means forconnecting both oi said members with the device and for adjusting thedegree of power supplied to the other of said ac r tuators to a valuesubstantially equal to that supplied to said one actuator includingmovable means ior connecting said power-operated movable members, meansfor connecting said movable means with said device, and power controlmeans for the other of said actuators operable in response to relativemovement or said movable means and connecting means for controlling thesupply or power to theother of said actuators.

'6. rower-operated means for controlling the actuation of a deviceincluding a pair of power actuators each having a power-operated movablemember, power control means ior one or the actuators, and means forconnecting both. or said members with the device and for adjusting thedegree of power supplied to the other 01' said actuators to a valuesubstantially equal to that supplied to said one actuator includingmovable means for connecting said power-operated movable members,movable means for connecting the device with the first named movablemeans, and power control means for the other of .said actuators carriedby one of said movable means and provided with an operating elementhaving an operative connection with the other of said movable means,whereby the last named power control means is operable in accordancewith relative movement of said first and second named movable means.

4. Power-operated means for controlling the actuation of a deviceincluding .a pair of power actuators each having a p wer-operatedmovable member, power control means for one of said actuators, and meansfor connecting said power operated members with the device and forcontrolling the supply of power to the other of said actuators includina connecting memberhaving a connection with the power-operated member ofsaid one actuator and a connection with the power-operated member of theother of said actuators, a second connecting member having a connectionwith the device and a pivotal connection with the first named connectingmember, said pivotal connection being so positioned with respectto theother connections that the moments imparted to the first namedconnecting member by the power-operated members are equal and oppositeabout said pivotal connection whenthe same degree of power is suppliedto each of said actuators, power control means for the other of saidactuators, and an operative able member, power control means for one ofto connection between the last named power control means and one of saidconnecting members for operating said last named power control means inresponse to relative movement of said connecting members. I

5. Power-operated means for controlling the actuation of a deviceincluding a pair of power actuators each having a power-operated movablemember, power control means for one oi said actuators, and means forconnecting said power operated members with the device and forcontrolling the supply or power to the other of said actuators includinga connecting member having a connection with the power-operated memberof said one actuator and a connection with the power-operated member ofthe other of said actuators, a second connecting member having aconnection with the device and a pivotal connection with the first namedconnecting member,- said pivotal connection being so positioned withrespect to the other connections that the moments imparted to the firstnamed connecting member by the power-operated members are equal andopposite about said pivotal connection when the same degree of power issupplied to each of said actuators, and power control means for theother of said actuators carried by one of said connecting members andprovided with a control element having an operative connection with theother of said connecting members.

6. Power-operated means for controlling the actuation of a deviceincluding a pair of double acting power actuators each having apower-operated member movable in either direction. power control meansfor one of the actuators for selectively supplying power thereto to movethe power operated member thereof in one direction or the other, andmeans for connecting said power operated members with the device and forcontrolling the supply of power to the other of said actuators to movethe power-operated member thereof in one direction or the otherincluding a connecting member having a separate connection with each ofsaid power-operated members, a second connecting member connected withthe device and having a pivotal connection with the first namedconnecting member, and pivotal connection being so positionedintermediate said connections with said power-operated members as tobalance the moments acting on the first named connecting member aboutsaid pivotal connection when substantially the same degree of power issupplied to each of said actuators, and power control means for theother or said actuators carried by one. of said connecting members andoperatively connected with the other of said connecting members, saidlast named control means being operable in response to rotation of thefirst named connecting member in one direction or the other about saidpivotal-connection on movement of the poweroperated member of said oneactuator in one direction or the other to selectively control the supplyof power to said other actuator to move the power-operated memberthereof in the same direction as the power-operated member of said oneactuator.

7. Power-operated mechanism for controlling the actuation of a devicehaving a neutral position and means associated therewith for normal- 1ymaintaining the device in neutral position with a predetermined force,said mechanism including a pair of power actuators each having a poweroperated movable member, power control means for one of saidactuators,and means for connecting both or said members with the device and foradjusting the degree or power so! plied to the other of said actuatorsto a value substantially equal to that supplied to said one actuatorincluding movable means for connecting said power-operated movablemembers, means for connecting said movable means with said device, andpower control means for the other of said actuators operable in responseto relative movement of said movable means and connecting means forcontrolling the supply of power to the other of said actuators.

8. Power-operated mechanism for controlling the actuation of a deviceincluding a pair 01' fluid actuators each having a pressure responsivemember, a lever having a separate connection with each of the members, aconnecting member connected with the device and having a pivotalconnection with the lever intermediate said separate connections, thelengths of the lever arms on either side of the pivotal connection beinginversely proportional to theareas ot the pressure responsive members towhich they are connected, valve mechanism for controlling the supply offluid pressure to one of said actuators, a second valve mechanism forcontrollin the supply of fluid pressure to the other of said actuatorshaving a valve operating element, and an operative connection betweensaid element and lever whereby said second valve mechanism is controlledby movement of said lever about said pivotal connection.

9. Power-operated mechanism for controlling the actuation of a deviceincluding a pair of double acting fluid actuators each having a pres.

' sure responsive member, a lever having a separate connection with eachof said members, a. connecting member connected with the device andhaving a pivotal connection with the lever intermediate said separateconnections, the lengths of the lever arms on either side of saidpivotal connection being inversely proportional to the areas of thepressure responsive members to which they are connected, control valvemechanism for selectively controlling the supply of fluid pressure toone of said actuators to effect movement of the pressure responsivemember thereof in one direction or the other, and means for controllingthe operation of the other of said actuators including valve mechanismoperable on rotation of said lever about said pivotal-connection bymovement of the pressure responsive member of said one actuator in onedirection or the other to supply fluid pressure to the other 01' saidactuators to effect movement 01' the pressure responsive member thereofin the same direction.

10. Power-operated mechanism for controlling the actuation of a deviceincluding a pair of double acting fluid actuators each having a pressureresponsive member, a lever having a separate connection with each ofsaid members, a connecting member connected with the device and having apivotal connection with the lever intermediate said separateconnections. the lengths of the lever arms on either side of saidpivotal connection being inversely proportional to the areas of thepressure responsive members to which they are connected, a pair ofcontrol valves for selectively controlling the supply of fluid pressureto one of the actuators for effecting movement of the pressureresponsive member thereof in one direction or the other, and means forcontrolling the supply of fluid pressure to the other of said actuatorsto efiect movement of the pressure responsive member thereof in the samedirection as the pressure responsive member of said one actuatorincluding a pair of control valves carried by said connecting member,and means controlled by movement of said lever about said pivotalconnection for selectively operating said valves.

11. Power-operated mechanism for controlling the actuation of a deviceincluding a pair of double acting fluid actuators each having a pressureresponsive member, a lever having a separate connection with each ofsaid members, a

. connecting member connected with the device and having a pivotalconnection with the lever intermediate said separate connections, thelengths of the lever arms on either side of said pivotal connectionbeing inversely proportional to the areas of the pressure responsivemembers to which they are connected, a pair of control valves forselectively controlling the supply of fluid pressure to one of theactuators for effecting movement of the pressure responsive memberthereof in one direction or the other, and means for controlling thesupply of fluid pressure to the other or said actuators to eiTectmovement of the pressure responsive member thereof in the same directionas the pressure responsive member of said one actuator including a pairofcontrol valves carried by said connecting member, a valve operatingelement for each of said control valves, and an operative connectionbetween each of said elements and said lever.

12. Power-operated mechanism for controlling the actuation of a deviceincluding a pair of double acting fluid actuators each having a.pressure responsive member, a lever having a separate connection witheach of said members, a

connecting member connected with the device and having a pivotalconnection with the lever intermediate said separate connections, thelengths of the lever arms on either side of said pivotal connectionbeing inversely proportional to the areas of the pressure responsivemembers to which they are connected, preloaded resilient means fornormally maintaining said device in a neutral position with apredetermined force, and means for controlling thesupply of fluidpressure to said actuators to effect movement of the dc vice in onedirection or the other from neutral position including a pair of controlvalves for controlling the supply of fluid pressure to one of theactuators each having a valve operating element and a pressureresponsive member associated therewith, means for selectively operatingsaid control valves including a control lever and a separate preloadedresilient connection between said lever and each of said valve operatingelements, and a pair ofv control valves carried by said connectingmember for controlling the supply of fluid pressure to the other of saidactuators, each of the last named control valves having a valveoperating elementoperatively connected with said lever.

13.1Power-operated means for controlling the actuation of a deviceincluding a pair of power actuators each having a power-operated movablemember, power control means for one of said actuators, and means forconnecting said power operated members with the device and forcontrolling the supply of power to the other of said actuators includinga connecting member having a connection with the power-operated memberof said one actuator and a connection with the power-operated member ofthe other of said actuators, a second connecting member having aconnection with the device and a pivotal connection with the first namedconnecting member, said pivotal connection being so positioned withrespect to the other connections that the moments imparted .to the firstnamed connecting member by the power-operated members are equal andopposite about said pivotal connection when the same degree of power issupplied to each of said actuators, power control means for the other ofsaid actuators, an operative connection between the last named powercontrol means and one of said connecting members for operating said lastnamed power control means in response to relative movement of saidconnecting members, and means for limiting the degree of said relativemovement, whereby actuation of the device by said one actuator isinsuredin the event of failure or the supply of power to the other ofsaid actuators.

l4, Power-operated mechanism for controlling the actuation of a deviceincluding a pair of power actuators each having apower-operated movableelement, power control means for one of the actuators, means forconnecting the elements and device including an actuating memberconnected with the device and a second member connected with saidactuating member and with each of said elements, said second memberbeing adapted for relative movement with respect to said actuatingmember by said power-operated elements when the degree of power suppliedto said actuators varies from a predetermined ratio, and power controlmeans for the other of said actuators having a control element having anoperative connection with one of. said members and operable on relativemovement of said members to vary the degree of power supplied to theother of said actuators.

l5. Power-operated mechanism for controlling the actuation of a deviceincluding a pair of power actuators each having a power-operated movableelement, power control means for one of the actuators, means forconnecting the elements and device including an actuating memberconnected with the device and a second mem ber connected with saidactuating member and with each. of said elements, said second memberbeing adapted for relative movement with respect to said actuatingmember by said power-operated elements when the degree of power suppliedto said actuators varies from a predetermined ratio, and means forcontrolling the supply of power to the other of said actuators includingpower control means therefor carried by one of said members and providedwith a control element having an operative connection with the other ofsaid members.

16. Power-operated control mechanism for controlling the actuation of adevice including a pair of power actuators each having a poweroperatedmovable element, power control means for one of said actuators, andmeans for connecting said actuators and device and for controlling thesupply of power to the other of said actuators including a lever havingspaced connections with each of said elements, a pivotal connection withsaid device intermediate said spaced connections, and power controlmeans for the other of said actuators having an operating elementcontrolled by rotation of said lever about said pivotal connection.

17. Power-operated control mechanism for controlling the actuation of adevice including a pair of fluid actuators each having a pressure 16pressure to the other oi! said actuators provided with a control elementhaving an operative connection with one 01' said members.

WILFRED A. EATON.

REFERENCES CITED The" following references are of record in the file ofthis patent:

UNITED sums PATENTS Number Name Date Stevens Aug. 21, 1945

